Wars are a complex business. Ending a war always includes more than ending the fighting. As Fred Iklé wrote in his 1971 classic Every War Must End, it’s hard to fight a war, harder still to end one well. Countries that have experienced the intensity of war as Ukraine has do not just turn on a dime and return to so-called normal.

Media attention is primarily on the fighting in Ukraine. This is probably natural, but it shouldn’t be the focus of senior civil and military strategists. U.S. and NATO leaders, in coordination with Ukrainian President Volodymyr Zelenskyy’s administration, must ensure that offensive and supporting operations succeed to the degree that they have strategic impact.

To achieve such impact, Ukraine first must push Russian forces from the territory they’ve seized following the February 2022 illegal aggression. They also must threaten the areas illegally occupied in 2014—the Donbas and Crimea. Doing both increases the probability of Russian President Vladimir Putin seeing his potential defeat. Absent this kind of force, Putin and his regime are unlikely to negotiate.

But U.S. and NATO leaders should plan and prepare for a post-major combat operations transition period that could last at least months—and, if history is any judge, probably longer.

For example, the post-major combat operations period following the American Revolution lasted at least two years, from 1781 to 1783, when the last British troops withdrew from New York City. Major combat operations of the Civil War ended in 1865, but Reconstruction lasted at least 12 years, from 1865 to 1877—and some put the end date even later. The occupation of Japan and Germany following combat operations of World War II lasted about seven years, from 1945 to 1952.

Of course, Ukraine is different from each of these examples. So, too, will be the length and composition of its post-major combat operations transition period. The point is, though, there will be a transition period, and Ukraine and allied leaders should begin now to consider its potential form and length as well as consequential demands it will put on all concerned.

Who Gets What

The first issue in the Russia-Ukraine war, and probably the most important and most difficult, is for allied and Ukrainian leaders to agree—secretly among themselves—what will be fought over and what will be negotiated. Certainly, justice demands that Russia relinquish all its ill-gotten Ukrainian territory, and the Zelenskyy government has every legal right to fight for that end.

Further, the allies are on strong moral and legal ground to assist Ukraine toward that end. This is not a proxy war; it is a war of self-defense for Ukraine and justified defense of others for the allies. But in addition to legal and moral issues, prudence also plays a part in war.

War costs lives and money, and no government can ignore these costs. The rhetoric from Ukraine is maximalist: Take back every inch of territory stolen by Russia. This is an understandable position, but at some point, prudence may convince Ukrainian leaders that a different solution is acceptable. That “different solution” includes a range of possible conditions best left to confidential diplomatic discussions.

Whatever solutions Ukraine and its allies end up agreeing to, however, must provide sufficient territory, sovereignty and security to guarantee Ukraine’s future economic prosperity and independence.

Right now, the American position is Ukraine will dictate when fighting ends. This also is an understandable position but it, too, may change as prudence begins to influence the conversation within allied capitals, among NATO political leaders and between the allies and the Ukrainian government.

Resolution of this primary issue, however, is only the beginning of figuring out what the post-major combat operations transitional period in Ukraine will look like.

Civilians in Crisis

Of immediate concern will be humanitarian assistance and rebuilding Ukraine’s housing and civil infrastructure. Discussion of this topic has begun. A large part of the dialogue centers on engineering and construction. But this topic is not devoid of political considerations. Contracts are involved and, therefore, money.

Who gets what contracts and how money is spent are hugely political issues, as is the question of how much recovery money provided to Ukraine takes the form of grants, and how much loans. Nations that have helped Ukraine defend its territory and sovereignty will want some form of return on their investment. This is natural. Russia likely will not be forced to pay reparations, so the financial issue is one Ukraine and its allies must work out.

Part of the solution will be to ensure contracts are let and monies spent to help regrow Ukraine’s economy and business capacity. Another part will entail limiting the probability of corruption—always a problem in these kinds of situations. Such requirements argue for some sort of joint Ukraine-allied recovery commission. There are many “equities” involved in such a massive project—especially one that will last years. A joint Ukraine-allied commission can increase the probability of a fair and balanced recovery on as quick a timeline as possible.

Fighting May Continue

As complex as humanitarian assistance and rebuilding may be, the post-major combat operations transition period in Ukraine will include other difficult tasks. Major combat may end with a formal or de facto cease-fire agreement or some other diplomatic arrangement. Negotiating that arrangement will take time, and as the diplomats negotiate terms, the war will not be over. Tensions, skirmishing and perhaps fighting by forces will continue. All transition periods include low-level fighting—kinetic and nonkinetic—of some sort, and Ukraine will be no different.

Putin cannot be trusted. He wants to subjugate Ukraine. His chosen method has been major combat, but if that’s taken from him, he will “fight” by other means. For example, he could use the return of refugees, prisoners of war and evacuated Ukrainian children, as well as protections for Russians in Ukrainian territory, as ways to throw sand in negotiations. He could conduct limited false flag operations. He could continue to block delivery of humanitarian assistance; he could use “deniable forces” like paid criminals or street thugs to muck up the peace and extend suffering.

And he could use cyber, legal and diplomatic actions to drag out negotiations and stymie post-major combat operations transitional activities. He can be expected to do everything in his power to hide the crimes his forces have committed. All these forms of disruptive actions, as well as others, have been present throughout history during other post-fighting periods. We can expect Putin to use them all.

Ukrainian and allied leaders should plan and prepare for such disruptions. An extended negotiation period may require employment of transitional military forces along zones of separation. It also may require reconstituting Ukraine’s military forces with training, equipment and, perhaps, some repositioning.

And if Ukraine’s military needs this, so will Russian forces—which leads to another set of complications and potential negotiating obstacles. Ukraine’s post-major combat operations transition period needs a secure environment for it to succeed. Such an environment must be created; it will not arise naturally.

Finally, Putin’s aggressive desire to recreate a Russian empire, which requires resubjugation of now free and sovereign states, will not fully abate even if he is foiled in his most recent attempt. Look at how Putin is trying to destabilize Moldova, setting the information space for future aggression. To prevent future aggression, Ukraine requires a clear and binding set of security guarantees.

Shattered Economy

Ukraine’s recovery is not limited to humanitarian assistance, reconstruction and security. The war has created deep fissures in Ukraine’s economy—from manufacturing to agriculture to distribution by air, ground, rail and sea, to banking and governmental spending, to personal consumption and corporate investments.

Furthermore, Ukraine’s casualties have been the teachers, nurses, school and hospital administrators, factory workers and foremen, dockworkers, bankers and a host of other key members of the workforce needed for recovery. All this must right itself in a post-major combat operations Ukrainian transition period.

The war also has created deep societal trauma. No society can absorb the kind of destruction and death; constant, random assault on innocent civilians, homes, hospitals, schools, nurseries and other normal life-support facilities; and extensive and yet-to-be fully documented war crimes without effect.

What form the effects of trauma take is not predictable. Social trauma indeed will emerge at the end of major combat operations, and this trauma will be deep and long-lasting. Ukraine’s local political leaders, police and religious and social support organizations will have to face this trauma, which will begin to emerge in the post-major combat operations transition period but last for many years after. Coordination and planning can begin now, with the appropriate international and nongovernmental organizations.

U.S., NATO and other allied leaders can avoid making the mistake of believing the war will be over when the fighting stops by planning now for the inevitable, post-major combat operations transition period.

Further, planning for a comprehensive and extended transition period—likely necessary when the time for negotiations finally comes—allows the allies to increase the probability of a long-lasting and stable peace. Only such a peace will give meaning to sacrifices Putin’s illegal aggression has forced upon the Ukrainian people and provide hope for a better future.

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Lt. Gen. James Dubik, U.S. Army retired, a former commander of Multi-National Security Transition Command-Iraq, is a senior fellow of the Association of the U.S. Army. He holds a doctorate in philosophy from Johns Hopkins University, Baltimore, and is the author of Just War Reconsidered: Strategy, Ethics, and Theory.